It sounds like you need to change the settings for your keyboard in Excel. Here's how you can do it:

1. Open Excel and click on the "File" tab in the top left corner.
2. Click on "Options" in the left-hand menu.
3. In the Excel Options window, click on "Advanced" in the left-hand menu.
4. Scroll down to the "Editing options" section.
5. Check the box next to "After pressing Enter, move selection".
6. Use the drop-down menu next to the checkbox to select "Down" if you want the cursor to move to the cell below, or "Right" if you want it to move to the cell to the right.
7. Click "OK" to save your changes.

Now, when you press the Enter key, the cursor should move to the next cell in the direction you selected. If you want to change this setting back to the default, simply uncheck the box next to "After pressing Enter, move selection" and click "OK".